In the parent application, which is incorporated in its entirety herein by reference, there is described a method and device for accelerating a two-phase mixture of at least two fluids moving with subsonic velocity to sound velocity, then accelerating it to supersonic velocity such that the mixture is brought to a final pressure through a pressure jump (or shock wave) substantially as a one-phase mixture.
One of the fluids in the two-phase mixture is referred to as an "active" fluid, and the other fluid is referred to as a "passive" fluid. Typically, but not always, the active fluid is gas that supplies energy for transporting the passive fluid, which is a liquid.
The apparatus disclosed in the parent application takes advantage of the physical phenomenon of an enhanced compression in homogenous two-phase flows or mixtures. In such mixtures, the sound velocity is lower than in either only the liquids or gases (vapors).
The compressibility of a flowing medium is represented by Mach number, denoted as "M," which corresponds to the ratio of flow speed and of the local sound velocity in the flowing fluid or fluid mixture. Since in the homogeneous two-phase mixtures, the sound velocity is very low, it is possible to achieve supersonic effects in such mixtures (with M greater than 1) by applying relatively low energy.
The increase of the Mach number is obtained in conventional jets or turbines by increasing the flow velocity, i.e., by increasing the numerator of the Mach number ratio. With the apparatus disclosed in the parent application a supersonic effect is obtained by lowering the sonic speed of the Mach ratio. This allows reducing the expenditure of energy for achieving the supersonic effects in comparison with conventional systems. Note also that the intensity of a shock wave (pressure jump) is proportional to the square of the Mach number, i.e. the ratio of the pressure at the rear of the shock wave and of the pressure in front of the shock wave is proportional to the square of the Mach number.
The apparatus described in the parent application comprises a nozzle coaxially connected to a feed line for mixing at least two fluids. An expansion chamber is provided downstream of the narrowest cross-sectional area at the outlet side of the nozzle. An outlet channel having a constant cross-sectional area is connected to the expansion chamber. The hydraulic diameter of constant cross-sectional area of the channel is as great as or up to three times as great as the hydraulic diameter of the narrowest cross-sectional area of the nozzle. Also, an outlet is connected with the expansion chamber and provided with a relief valve.
In this apparatus the static pressure P.sub.ck in the rear of the shock wave is adjusted such that it is greater than the static pressure P.sub.l in front of the shock wave and is less than the half of the sum of the static pressure P.sub.l in front of the shock wave and of the stagnation pressure P.sub.o in the rear of the shock wave or is equal to the half of this sum.
It is possible to achieve the desired fluid action substantially independently of changes of the outside pressure and end pressure. A stable operation with constant flow rates of the fluids in this device is obtained if the outer pressure or end pressure P.sub.np is greater than the static pressure P.sub.l, in front of the shock wave but less than the static pressure P.sub.ck, in the rear of the shock wave or is equal to this pressure P.sub.ck, wherein within these pressure ranges the pressure of the two-phase mixture expanded to its supersonic velocity is not released.
There are certain drawbacks associated with the apparatus disclosed in the parent application. First, the proper ratio of fluids in the mixture and the pressure jump is achieved due to the geometric design of the system. Thus, the apparatus typically can handle only the fluids having relatively inflexible parameters, such as pressure and temperature. If the parameters of the fluids and/or the environment at the outlet of the system change, then a new apparatus would need to be designed and built.
Furthermore, the apparatus disclosed in the parent application is unable to create a stable pressure jump if the temperature of the passive fluid is higher than the temperature of the active fluid, or the temperatures of both fluids are approximately the same. Under such conditions gas condenses so that it is difficult to maintain a proper ratio of the gas and liquid phases in the mixture such that the sonic velocity of the mixture is reduced as required for a stable pressure jump. Also, the condensation of the active fluid causes the decrease of the stagnation pressure of the mixture. The stagnation pressure determines the intensity of the pressure jump.
As indicated, in the apparatus disclosed in the parent application, the intensity of the pressure jump is determined by the geometrical dimensions of the device and the parameters of the fluids. However, such a device does not provide a facility for varying the intensity of the pressure jump. I have invented a device which overcomes the disadvantages and limitations of the aforementioned apparatus.